1. Field of the Invention
The present invention relates to a high-frequency treatment device which is inserted into a body cavity through a channel of an endoscope and executes incision and excision of a mucous membrane in the body while delivering a high-frequency current.
2. Description of the Related Art
Devices that are inserted into a body cavity through the channel of the endoscope and execute incision and excision of living tissues in the body such as diseased mucous membranes include the following treatment devices. For example, a high-frequency snare is disclosed in Jpn. UM. Appln. KOKAI Publication No. 5-13410. A loop-shaped wire is provided at a distal end of an operation wire of the high-frequency snare. A living tissue is tied up with the loop-shaped wire, and the living tissue is excised while delivering a high-frequency current through the loop-shaped wire.
Jpn. Pat. Appln. KOKAI Publication No. 3-146046 discloses a pair of forceps with scissors. These forceps mechanically excise the living tissue by the shear force of a pair of scissors. Alternatively, Jpn. Pat. Appln. KOKAI Publication No. 2000-14678 discloses another high-frequency treatment device. This high-frequency treatment device can excise the living tissue by delivering a high-frequency current through a pair of partially insulated forceps.
Jpn. UM. Appln. KOKAI Publication No. 5-11913 discloses another high-frequency treatment device. This high-frequency treatment device is provided with a bipolar excision portion capable of closing and opening by protruding from and retracting into a distal end of a sheath. A pair of electrode members individually formed using a filament of wire is provided at the bipolar excision portion.
It is necessary for excising the living tissue such as the mucous membrane to confirm whether or not entire lesions are completely excised in order to prevent disease from recurring. For this purpose, it is required to reconstruct an excised piece to its original shape after the excision to confirm that the lesions are localized in the excised piece. Therefore, excision of the tissue takes a long time. An operation for excising a relatively large area of the living tissue is required for excising the entire lesions.
However, the entire lesions cannot be excised by a single operation with one attempt to excise a diseased mucous membrane having a wider area than the loop diameter using the high-frequency snare. Consequently, the living tissue should be excised in portions through plural operations. Not only does such repeated excision work require much time, but also the excised pieces may be dismembered. It is also difficult to precisely reassemble the dismembered excision pieces into their original shape after the excision. Accordingly, a treatment method capable of collectively excising a wide area of the mucous membrane, which is impossible by the high-frequency snare method, is required.
It is possible to proceed to cut the diseased mucous membrane little by little with a pair of forceps with scissors in order to collectively excise a wide area of the mucous membrane. The pair of forceps with scissors to be used herein is slender, and the operation wire for opening and closing the pair of scissors of the forceps is inserted through the sheath, which is required to be flexible. Accordingly, when the sheath is bent in an arbitrary shape during use such as in the case of the endoscope, the operational force of the operation wire in the bent sheath may not be sufficiently transferred to the pair of scissors. Since the shear force for incising the living tissue is not sufficiently imparted to the portion of the pair of scissors, the tissue cannot be sharply incised, thereby making the incision work itself difficult. In addition, the tissue may bleed since the living tissue is mechanically excised with the pair of forceps with scissors.
As a countermeasure for the problems above, one may attempt to perform incision by delivering a high-frequency current through the scissors part of the forceps. When the tissue is excised by the high-frequency current, the electric current must be converged on the incision area. However, when the contact area with the mucous membrane is large as encountered in the scissors of the forceps, a smooth incision may be impossible or it may be difficult to excise only the desired portion of the tissue with high accuracy due to divergence of the electric current.
Alternatively, the problem above may be solved by converging the high-frequency current on the tip of the blade by insulating portions of the forceps other than the tip of the blade. However, there occurs another problem in that the treatment device generates a high temperature by delivering the high-frequency current. In addition, since the scissors are in sliding contact with each other, a complicated and specified processing is required for applying an insulating coating on the scissors part. Therefore, the forceps with the scissors become very expensive.
It is also difficult to handle the incision portion with high accuracy by the method disclosed in Jpn. UM. Appln. KOKAI Publication No. 5-11913, because the wire used for the bipolar incision portion is so fine that the required elasticity cannot be obtained and the direction in which the pair of electrode members is opened is unstable. Furthermore, the opening width of such a treatment device is so narrow that a wide area of living tissue cannot be grasped. Therefore, a long time is required for excising a wide area of living tissue while making the incision work itself unstable.
Accordingly, it is an object of the present invention, carried out considering the situations as hitherto described, to provide a high-frequency treatment device capable of collectively excising a living tissue such as a wide area of a mucous membrane safely and smoothly using an endoscope.
In order to achieve the above object, the present invention provides a high-frequency treatment device comprising a slender insertion portion to be inserted into a body cavity through a channel of an endoscope; an incision portion which is disposed at a distal end of the insertion portion and which executes incision and excision of a mucous membrane in the body while delivering a high-frequency current; and an operation portion which is disposed at a proximal end of the insertion portion and which manipulates the incision portion, wherein the insertion portion has a soft sheath and an operation wire inserted through the soft sheath to be movable in the axial direction. The incision portion has: a pair of opening and closing elements connected to the distal end of the operation wire and capable of opening and closing by protruding from and retracting into the distal end of the soft sheath, each opening and closing element having a slender and plate-shaped arm and a high-frequency surgical blade disposed at the distal end of the arm; and a high-frequency treatment portion which allows the high-frequency current to converge on the blade; and the operation portion comprises a switching member which switches from an opening operation position, at which the opening and closing elements are deformed into an open state which allows the blades of each opening and closing element to be separated from each other by protruding each opening and closing element from the distal end of the soft sheath by a push-out operation of the operation wire toward a distal side, to a closing operation position, at which the opening and closing elements are deformed into a closed state which allows the blades of each opening and closing element to close with each other by retracting each opening and closing element into the soft sheath by a pull-in operation of the operation wire in a proximal side, or vice versa.
Accordingly, in the present invention, when lesions are found by an observation with the endoscope, the insertion portion of the treatment device is inserted into the channel of the endoscope, and the treatment device is guided into the body cavity. After guiding the distal end of the insertion portion in the vicinity of the surface of the living tissue to be incised under observation with the endoscope, the opening and closing element is projected from the distal end of the soft sheath to open the opening and closing element. After pressing the opening and closing element onto the lesions to be excised while the element is open, the opening and closing element is closed by pulling the element into the sheath to grasp only the portion to be incised. A high-frequency current is then supplied to converge it on the high-frequency surgery part of the blade, thereby incising the mucous membrane. A wide area of lesions are completely excised as one block without dismembering the lesions.
Therefore, the present invention enables the living tissues such as a wide area of the mucous membrane to be collectively excised safely and smoothly; the addition the surgical operation is inexpensive.
Furthermore, the high-frequency treatment device according to the present invention has a small width portion in which the width of the blade is smaller than that of the arm. The lesions are sharply and reliably incised by converging a high-frequency current on the narrow part of the blade having a smaller width than the width of the arm during the high-frequency surgical operation.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.